To understand the dismal situation in today’s Iraq — the unimpeded ISIS rampage, a government incapable of addressing bitter factionalism, and unbridled religious and ethnic hatred — it’s necessary to take a look at history. And not the narrow, decade-old conception of history that has become increasingly popular among commentators.

Some decry President Bush’s strategic blunders. Others lament President Obama’s withdrawal of American troops in 2011. But ultimately, Saddam Hussein’s incessant efforts to incite sectarianism and religious hatred in Iraq — a savage policy known as “divide and rule” — are to blame for the desperate situation today.

This vicious process started in 1968 with Saddam’s violent marginalization of Iraq’s Shiite population. Throughout the 1970s, the Shiite Iraqi Dawa Party was committed to the establishment of an Islamic state in Iraq (sound familiar?). This was, of course, anathema to the regime, which responded with coercion and bloodshed. Members of the Dawa Party were routinely assassinated, and the regime constantly fabricated stories about attempts on Saddam’s life — as well as plots to overthrow the Baath Party — each avenged with a public execution. This murderous, fear-based campaign intensified after the Iranian revolution in 1979.

Joseph A. Kéchichian, an analyst at the Middle East Institute, recently argued that Saddam “played up religious and ethnic division at every turn. More than six years after his death, surging Sunni-Shia violence is a bloody consequence.”

During the Iran-Iraq war (1980 to 1988) — a time when spurring Arab nationalism was more important to the regime than catalyzing brutal sectarianism — Saddam was less aggressive toward the Shiites. But this is when he committed his most nauseating crime: The genocidal Anfal (“spoils of war”) campaign against Iraq’s Kurdish population. Both conventional and chemical weapons were used to exterminate as many as 180,000 Kurds in northern Iraq. Yet another horrendous crime, yet another bottomless political and social rift. And this ghastly atrocity was met with American indifference, as Saddam was then an ally against Iran.

Then, after the Gulf War, an insurrection of Shiites in the south and Kurds in the north — stirred by encouragement from President George H.W. Bush and the presence of coalition forces — resulted in the slaughter of more than 60,000 people (often via indiscriminate bombings, kerosene attacks and the intentional massacre of civilians).

The atomization of Iraqi society, perpetually exacerbated by the state, is the foundation of today’s dangerous state of affairs. To blame the civil war on either the Bush or the Obama administration is to miss the point — these tensions were gurgling and seething beneath the surface of Iraqi society for half a century, all the while being deepened and protracted by the regime.

Even if you’re prepared to argue that Iraq would have been better off under Saddam Hussein or one of his verminous sons for the next few decades, you’re still not circumventing the problem of sectarianism. If the only bulwark against civil conflict in Iraq was a genocidal maniac and his sadistic family, who presided over what the Iraqi scholar Kanan Makiya accurately called a “Republic of Fear,” the situation was both tragic and tenuous. Unless Iraq was going to remain in this terrorized, volatile state forever, severe civil strife was in its future.

Regarding the current disaster, blame Prime Minister Nouri al-Maliki for the grievous mistake of pushing Sunnis to the threshold of disloyalty and resentment by excluding them from the government. Blame the United States’ reluctance to intervene in Syria or at least reinforce the Iraqi border to stem the inflow of ISIS fighters. Blame the Bush administration for what journalist and analyst Tom Ricks called, “The worst war plan in American history.” But don’t blame the United States for removing the toxic glue of pre-2003 Iraqi society — the glue of totalitarianism, manipulation and fear — and for the enmity and disintegration sowed by Saddam Hussein.